It's a kind of medical miracle--some HIV-positive patients live for years with minimal symptoms or no symptoms at all. How do they do it? If researchers could figure that out, they might be able to recreate this resistance to HIV in others, effectively preventing the illness. Using an exciting new tool--a whole genome scan--scientists are combing the entire human genome to look for all of the genes that might contribute to HIV resistance. A global leader in that effort gives us a status report from the lab bench. Hosted by Paul Raeburn.